can someone tell me what the stock lift on a vortec head is, casting 906? also will my stock center bolt valve covers off a 91 z fit on these heads and can i use 1.6 rockers with them at say 490(if they can take that lift stock or not i will get them milled to work) max lift with the stock covers, i have searched but could not find my answers, thanx if u can help

 

Factory lift is ~.450"-.480" as cast. 1.6 rockers depends on if it will take the valve lift that far. I would have them milled for anything .470" or more.

VC's should fit.

 

bone stock vortec truck with zz4 cam 474/510 no problems at all!

 

Ive read that if your going to have a valve lift over .450 you should have the valve guides machined for guide to seal clearance, and also have the pushrod holes elongated on vortec heads.

 

You mill the guide bosses for more room between the guide boss and the bottom of the retainer.

Only elongate the pushrod slots if you plan on running 1.6 rockers. You make them larger overall if you run guide plates.

 

You mill the guide bosses for more room between the guide and the bottom of the retainer.

Only elongate the pushrod slots if you plan on running 1.6 rockers. You make them larger overall if you run guide plates.

 

I just barely cleared .454 @ .050 on my Vortecs.

Had to slot the pushrod slots as well. Nothing unusual about my setup except an aftermarket roller cam and matching pushrods.

Even at .454 I was just under the recommended minimum clearance (can't recall, is it the thickness of a penny?) but since this is not a high RPM motor, I decided to run it. No problems so far.

There seems to be a LOT of difference in the Vortec heads for some reason.

Stock lift was something like .420, and the stock springs are very weak as a result.

 

Right, He asked if he could use 1.6 rockers with vortec heads.